Although surgery is the treatment of choice for severe obesity, very little is known about the relationship of lifestyle factors to patient outcomes after operation. This Mentored Patient-Oriented Research Career Development Award (K23) describes integrated training and research plans designed to prepare the candidate to pursue research on helping patients achieve optimal weight loss and lifestyle adjustment after bariatric surgery. A model of treatment is presented in which an intervention targeting behavioral (eating, activity, and compliance) and psychosocial factors (e.g., symptoms of binge eating and personality style) is expected to impact weight loss, health-related quality of life, and overall well-being. Advanced training in genetic and environmental influences on severe obesity, an expanded working knowledge of how surgeons treat severely obese patients, and consolidation of skills in longitudinal research methodology will assist in refining and developing this model. The research plan involves prospectively tracking weight-related variables, eating and activity, compliance and satisfaction, and psychosocial factors over time among a group severely obese patients undergoing surgery for weight loss (Study 1), and using the data to inform the development and evaluation of a lifestyle intervention geared to optimizing outcomes after operation (Study 2). The comprehensive lifestyle intervention will encompass 1) encouraging healthy eating habits, 2) increasing physical activity, 3) enhancing psychosocial adjustment. Adaptations to treatment will accommodate the unique needs of bariatric surgery patients. Specifically, a modular treatment format will address patients' changing needs in the preoperative, postoperative, and longer-term adjustment phases. Additionally, the intervention will be developed for delivery one-on-one at routine clinic visits with supplemental contact via the Internet. The data collected will contribute to the preparation of an R01 application that will involve conducting a full-scale randomized clinical trial to evaluate the modular, computer-aided lifestyle intervention. Future work may focus on adding adjunctive treatment components such as weight loss medication, the effects of which have not been adequately studied in bariatric surgery patients.